lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

UBI: add UBI devices reference counting

Browse Source 
This is one more step on the way to "removable" UBI devices. It
adds reference counting for UBI devices. Every time a volume on
this device is opened - the device's refcount is increased. It
is also increased if someone is reading any sysfs file of this
UBI device or of one of its volumes.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
This commit is contained in:
Artem Bityutskiy
2007-12-17 17:37:26 +02:00
parent 9f961b5756
commit e73f4459d9
7 changed files with 201 additions and 63 deletions
Download Patch File Download Diff File Expand all files Collapse all files

142
drivers/mtd/ubi/build.c
View File

@@ -64,9 +64,6 @@ static int mtd_devs = 0;
/* MTD devices specification parameters */
static struct mtd_dev_param mtd_dev_param[UBI_MAX_DEVICES];
/* All UBI devices in system */
struct ubi_device *ubi_devices[UBI_MAX_DEVICES];
/* Root UBI "class" object (corresponds to '/<sysfs>/class/ubi/') */
struct class *ubi_class;
@@ -83,6 +80,12 @@ static struct miscdevice ubi_ctrl_cdev = {
.fops = &ubi_ctrl_cdev_operations,
};
/* All UBI devices in system */
static struct ubi_device *ubi_devices[UBI_MAX_DEVICES];
/* Protects @ubi_devices and @ubi->ref_count */
static DEFINE_SPINLOCK(ubi_devices_lock);
/* "Show" method for files in '/<sysfs>/class/ubi/' */
static ssize_t ubi_version_show(struct class *class, char *buf)
{
@@ -118,37 +121,145 @@ static struct device_attribute dev_min_io_size =
static struct device_attribute dev_bgt_enabled =
__ATTR(bgt_enabled, S_IRUGO, dev_attribute_show, NULL);
/**
* ubi_get_device - get UBI device.
* @ubi_num: UBI device number
*
* This function returns UBI device description object for UBI device number
* @ubi_num, or %NULL if the device does not exist. This function increases the
* device reference count to prevent removal of the device. In other words, the
* device cannot be removed if its reference count is not zero.
*/
struct ubi_device *ubi_get_device(int ubi_num)
{
struct ubi_device *ubi;
spin_lock(&ubi_devices_lock);
ubi = ubi_devices[ubi_num];
if (ubi) {
ubi_assert(ubi->ref_count >= 0);
ubi->ref_count += 1;
get_device(&ubi->dev);
}
spin_unlock(&ubi_devices_lock);
return ubi;
}
/**
* ubi_put_device - drop an UBI device reference.
* @ubi: UBI device description object
*/
void ubi_put_device(struct ubi_device *ubi)
{
spin_lock(&ubi_devices_lock);
ubi->ref_count -= 1;
put_device(&ubi->dev);
spin_unlock(&ubi_devices_lock);
}
/**
* ubi_get_by_major - get UBI device description object by character device
* major number.
* @major: major number
*
* This function is similar to 'ubi_get_device()', but it searches the device
* by its major number.
*/
struct ubi_device *ubi_get_by_major(int major)
{
int i;
struct ubi_device *ubi;
spin_lock(&ubi_devices_lock);
for (i = 0; i < UBI_MAX_DEVICES; i++) {
ubi = ubi_devices[i];
if (ubi && MAJOR(ubi->cdev.dev) == major) {
ubi_assert(ubi->ref_count >= 0);
ubi->ref_count += 1;
get_device(&ubi->dev);
spin_unlock(&ubi_devices_lock);
return ubi;
}
}
spin_unlock(&ubi_devices_lock);
return NULL;
}
/**
* ubi_major2num - get UBI device number by character device major number.
* @major: major number
*
* This function searches UBI device number object by its major number. If UBI
* device was not found, this function returns -ENODEV, othewise the UBI device
* number is returned.
*/
int ubi_major2num(int major)
{
int i, ubi_num = -ENODEV;
spin_lock(&ubi_devices_lock);
for (i = 0; i < UBI_MAX_DEVICES; i++) {
struct ubi_device *ubi = ubi_devices[i];
if (ubi && MAJOR(ubi->cdev.dev) == major) {
ubi_num = ubi->ubi_num;
break;
}
}
spin_unlock(&ubi_devices_lock);
return ubi_num;
}
/* "Show" method for files in '/<sysfs>/class/ubi/ubiX/' */
static ssize_t dev_attribute_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
const struct ubi_device *ubi;
ssize_t ret;
struct ubi_device *ubi;
/*
* The below code looks weird, but it actually makes sense. We get the
* UBI device reference from the contained 'struct ubi_device'. But it
* is unclear if the device was removed or not yet. Indeed, if the
* device was removed before we increased its reference count,
* 'ubi_get_device()' will return -ENODEV and we fail.
*
* Remember, 'struct ubi_device' is freed in the release function, so
* we still can use 'ubi->ubi_num'.
*/
ubi = container_of(dev, struct ubi_device, dev);
ubi = ubi_get_device(ubi->ubi_num);
if (!ubi)
return -ENODEV;
if (attr == &dev_eraseblock_size)
return sprintf(buf, "%d\n", ubi->leb_size);
ret = sprintf(buf, "%d\n", ubi->leb_size);
else if (attr == &dev_avail_eraseblocks)
return sprintf(buf, "%d\n", ubi->avail_pebs);
ret = sprintf(buf, "%d\n", ubi->avail_pebs);
else if (attr == &dev_total_eraseblocks)
return sprintf(buf, "%d\n", ubi->good_peb_count);
ret = sprintf(buf, "%d\n", ubi->good_peb_count);
else if (attr == &dev_volumes_count)
return sprintf(buf, "%d\n", ubi->vol_count);
ret = sprintf(buf, "%d\n", ubi->vol_count);
else if (attr == &dev_max_ec)
return sprintf(buf, "%d\n", ubi->max_ec);
ret = sprintf(buf, "%d\n", ubi->max_ec);
else if (attr == &dev_reserved_for_bad)
return sprintf(buf, "%d\n", ubi->beb_rsvd_pebs);
ret = sprintf(buf, "%d\n", ubi->beb_rsvd_pebs);
else if (attr == &dev_bad_peb_count)
return sprintf(buf, "%d\n", ubi->bad_peb_count);
ret = sprintf(buf, "%d\n", ubi->bad_peb_count);
else if (attr == &dev_max_vol_count)
return sprintf(buf, "%d\n", ubi->vtbl_slots);
ret = sprintf(buf, "%d\n", ubi->vtbl_slots);
else if (attr == &dev_min_io_size)
return sprintf(buf, "%d\n", ubi->min_io_size);
ret = sprintf(buf, "%d\n", ubi->min_io_size);
else if (attr == &dev_bgt_enabled)
return sprintf(buf, "%d\n", ubi->thread_enabled);
ret = sprintf(buf, "%d\n", ubi->thread_enabled);
else
BUG();
return 0;
ubi_put_device(ubi);
return ret;
}
/* Fake "release" method for UBI devices */
@@ -670,6 +781,7 @@ static void detach_mtd_dev(struct ubi_device *ubi)
int ubi_num = ubi->ubi_num, mtd_num = ubi->mtd->index;
dbg_msg("detaching mtd%d from ubi%d", ubi->mtd->index, ubi_num);
ubi_assert(ubi->ref_count == 0);
uif_close(ubi);
ubi_eba_close(ubi);
ubi_wl_close(ubi);